Emergent Physics in Correlated, Spin-orbit Coupled Materials

*技术摘要*本项目的重点是自旋-轨道耦合系统，其中关联是相关的。虽然最近有许多理论研究描述了这类材料中的新相，但还没有一个有趣的预测，如Weyl半金属状态或轴子绝缘体，到目前为止还没有观察到。低温扫描隧道显微镜(STM)是研究复杂材料电子结构的最好方法之一，而复杂材料的电子结构往往表现出纳米尺度的不均匀。扫描隧道显微镜将被用于研究相关的自旋轨道材料，如焦绿石和Ruddlesden-Popper系列铁酸盐，或Heusler化合物。在理解这些系统的基本性质方面的进展可能导致在自旋-轨道耦合的复杂系统中出现新的范式。通过理论合作者的密切反馈和在获得单晶和薄膜样品方面的快速周转，该小组将能够迅速探索各种材料，以寻找新的相。综合教育活动包括为博士后制定新的全系指导计划，让本科生参与研究，这将有助于培养下一代科学家，以及通过教育学院正在进行的外展计划，这将对初中和高中训练有素的科学教师的数量产生可衡量的影响。*非技术摘要*探索固体中电子和原子物理的一个新的令人兴奋的前沿是探索存在不止一种主导相互作用的材料。自旋-轨道耦合是电子的量子力学自旋与其轨道性质之间的相互作用。当自旋-轨道相互作用很强时，材料就会显示出新奇的效应。然而，将电子-电子相互作用添加到这些体系中可以极大地扩展新性质的范围。虽然最近有很多关于这类材料中可能出现的新状态的理论研究，但到目前为止还很少进行实验研究。此外，到目前为止，还没有一个有趣的预测阶段被实验观察到。这个项目专注于材料的基本物理，其中有多种相互作用，它们既可以相互竞争，也可以相互帮助。为了研究这些材料，我们将使用扫描隧道显微镜的工具，它不仅可以成像单个原子，还可以移动单个原子来建立人工原子尺度结构。任何对新状态的发现和对其性质的了解，对于推进我们在这一新领域的知识都是至关重要的。这个项目将支持研究生和博士后，他们将学习实验技术和当前研究的前沿材料物理。

****Technical Abstract****This project focuses on spin-orbit coupled systems where correlations are relevant. While there have been many recent theoretical studies describing novel phases in such materials, none of the intriguing predictions such as the Weyl semi-metal state or axion insulators has as yet been experimentally observed. Low temperature scanning tunneling microscopy (STM) is one of the best methods to probe the electronic structure of complex materials, which often exhibit nanoscale inhomogeneities. STM will be used to study correlated spin-orbit materials such as the pyrochlore and Ruddlesden-Popper series of iridates, or the Heusler compounds. Progress in understanding fundamental properties of these systems may lead to new paradigms in spin-orbit coupled complex systems. With close feedback from theory collaborators and quick turn around in obtaining single crystal and thin film samples, the group will rapidly be able to explore a variety of materials in search of novel phases. The integrated education activities include a new structured department-wide mentoring plan for post-docs, and involvement of undergraduates in research, which will help train the next generation of scientists, as well as an ongoing outreach program through the School of Education, which will have a measurable impact on the numbers of trained science teachers in middle- and high schools.****Non-Technical Abstract****A new and exciting frontier in the exploring the physics of electrons and atoms in solids is the exploration of materials where there is more than one dominating interaction. Spin-orbit coupling is an interaction between the quantum mechanical spin of an electron and its orbital properties. When spin-orbit interaction is strong, materials are known to show novel effects. However, adding electron-electron interactions to these systems can vastly expand the range of novel properties. While there have been many recent theoretical studies on the possible new states in such materials, very few experimental studies have been carried out so far. Moreover, none of the intriguing predicted phases has as yet been experimentally observed. This project focuses on the fundamental physics of materials where with multiple interactions, which can either compete or aid one another. To study these materials we will use the tool of scanning tunneling microscopy, which has the power to not only image single atoms but also to move individual atoms to build artificial atomic scale structures. Any discoveries of novel states and understanding their properties will be vital to advancing our knowledge in this new field. This project will support graduate students and post-docs who will learn experimental techniques and the physics of materials at the cutting edge of current research.